EP2408565B1 - Hydraulic array for roller mills - Google Patents

Abstract

The invention relates to a hydraulic array for roller mills, having a spring unit (11) for each grinding roll, a gas/oil reservoir (16, 17) and hydraulic supply systems for changing the operation states of the spring units or grinding rolls. In order to ensure an almost constant crushing power and a uniform contact pressure of the grinding rolls and at the same time reduce the production and assembly costs and the risk of failure of the components of the hydraulic system and to improve the exchange of components or the entire system, each spring unit of a grinding roll is associated, in its proximity, with its proper hydraulic supply unit (20) as a compact hydraulic system and a reservoir station (22) so that the necessary connections can be realized by means of relatively short conduits (23) and high-pressure lines (24). Every hydraulic supply unit can be pre-assembled under dust-free ambient conditions and accommodated for example in a hydraulic cabinet (25) and only needs to be connected on site.

Description

The invention relates to a hydraulic arrangement of a roller mill according to the preamble of claim 1.

The invention is intended for Wälzmühlen in which comminuted between a rotating horizontal grinding track of a grinding bowl or a grinding table and stationary, rolling mill grinders and which as overflow mills with the Mahlteller- or Mahlschüsselrand down falling, crushed millbase or formed as air flow Wälzmühlen are in which the comminuted material to be ground in an air or gas stream is fed to a particular integrated classifier.

Particularly advantageously, the invention is suitable for large Wälzmühlen, which for example have a grinding bowl diameter of 2 m and more and three, four or six grinding rollers. Roller mills with a grinding bowl diameter of 4.1 and 4.3 m, for example, are known, on which four or six grinding rollers roll.

Air-jet rolling mills of the LOESCHE type with two, three, four or six grinding rollers are advantageously constructed in modular construction and, for example, made DE 31 00 341 A1 . DE 10 2004 062 400 B4 . U.S. Patent 6,021,968 and WO 2005/028112 A1 known.

Components of the modular design are grinding roller, rocker arm, in which the grinding roller axis is mounted, stand, on which the rocker arm is pivotally mounted, and a hydropneumatic suspension for generating the contact pressure or grinding pressure.

The hydropneumatic suspension has a suspension unit per grinding roller with one or two hydraulic cylinders depending on the size of the roller, gas / oil reservoir and a hydraulic supply system, which is connected via pipelines and high-pressure hoses with the suspension unit. Pumps, valves, shut-off devices, a control and operating elements of the hydraulic supply system allow the realization of different operating conditions of the hydraulic cylinder and thus raising the grinding rollers as a result of grinding bed based on the grinding, a lowering, for example in a grinding bed valley and lifting the grinding roller from the grinding path at the start of the mill drive, wherein in each case the working pressure or the back pressure is increased or decreased.

It is known that in a three-roll mill all rolls are connected to a hydraulic system ( DD-PS 106 953 ). In Wälzmühlen with two opposing grinding rollers, it is known to hydraulically connect these opposed grinding rollers together.

FIG. 6 shows a hydraulic scheme of a four-roll mill with the grinding rollers 1 to 4 and two hydraulic cabinets 5, 6. Here are the suspension cylinder (not shown) of the roller pair with the grinding rollers 1, 3 with the hydraulic cabinet 6 and the suspension cylinder (not shown) of the Roller pair with the grinding rollers 2, 4 connected to the hydraulic cabinet 5 and the respective associated gas / Ölspeichem (not shown).

These connections require high pressure hoses and piping. Ring lines 7, 8, which are usually laid around the mill foundation, connect the respective grinding rollers 1, 3 and 2, 4 with each other, and in each case a stub 9 leads to the associated hydraulic cabinet 5, 6th

The disadvantages of the known system with a hydraulic cabinet per pair of rollers are considerable costs for the manufacture and installation of the pipelines, in particular for the piping, a relatively high risk of failure of the components of the hydraulic system by contamination, which can not be completely avoided in the mounting conditions on site, and relatively unfavorable maintenance and replacement options of the hydraulic system or the individual components in case of defects.

The increase in the Wälzmühlen due to the increasing demands on their throughput is connected to even longer connecting / ring lines, which may cause disturbances in the grinding operation. Due to the up and down movement of the grinding rollers in the grinding operation, the hydraulic oil, which is expressed or sucked in from the suspension cylinders flows due to the lower line resistance primarily in the gas / oil reservoir, but partly also via the connecting pipe to the respective opposite suspension cylinder. Due to its inertia and resistances, the hydraulic oil can not flow sufficiently fast into the connecting pipes. The result is impermissibly high pressure peaks or cavitation phenomena, which lead to fluctuations in the oil pressure in the cylinder chambers and thus also to constantly changing comminution forces under the grinding rollers. As a result, the smooth running and production capacity of the roller mill are adversely affected.

If permissible vibration values are exceeded, the grinding rollers are also raised hydraulically out of engagement with the material to be ground when the pumps are started and the oil pressure in the lower cylinder chambers is increased. Due to different resistances, the grinding rolls lift successively, that is, the second grinding roller device only after a period of about one and a half minutes out of engagement with the material to be ground, in which case the first grinding roller has already reached an upper mechanical stop. Only then, however, is the smooth running of the roller mill restored. The lifting time of about one and a half minutes results from the selected pump capacity of the hydraulic supply unit and the volume to be replenished in the suspension cylinders and gas / oil reservoirs. However, a larger pump performance would be for the normal function "increase working pressure" of disadvantage, since even with a short time switching on a larger pump too much oil would be pumped into the system, with the result of a rapid pressure increase, which then exceeds the setpoint and re-command in the Hydraulic system "reduce working pressure" leads. This would provide a constant hysteresis in these switching operations.

The invention has for its object to eliminate by a hydraulic arrangement, the identified adverse effects on the smoothness and throughput and to ensure a nearly constant crushing force or a uniform contact pressure of the grinding rollers. At the same time, the Manufacturing and assembly costs, in particular for the pipelines are lowered, and the risk of failure of the components of the hydraulic system minimized and the maintenance and replacement of components or the entire system can be improved.

According to the invention the object is achieved by the features of claim 1. Advantageous and advantageous embodiments are contained in the subclaims and in the drawing figures.

A basic idea of the invention can be seen in the fact that, instead of the previous system with one hydraulic cabinet per pair of rollers and the necessary connection pipes and high-pressure hoses to the suspension units of the grinding rollers with one or two hydraulic cylinders each grinding roller or its suspension unit to assign a hydraulic supply unit as a compact unit, wherein in this compact unit all necessary supply and control components are integrated.

A storage stall, which advantageously has hydraulic bladder accumulator and hydraulic piston accumulator as a compact unit, can also be integrated in the hydraulic supply unit.

According to the invention, each suspension unit of a grinding roller of the roller mill is assigned its own hydraulic supply unit as a compact hydraulic system and a storage unit and arranged close to the location so that the necessary connections can be realized with the aid of relatively short pipes and high-pressure hoses.

It is advantageous that each hydraulic supply unit can be designed as a compact hydraulic unit and preassembled under dust-free ambient conditions, so that this preassembled compact unit, preferably accommodated in a hydraulic cabinet, only has to be connected on site. This largely avoids soiling and reduces the risk of failure.

It is particularly advantageous that each hydraulic cabinet fitted with the pre-assembled compact hydraulic on an oil tank, lifted off this and thus can be replaced in a particularly simple manner and with a relatively small amount of time, if necessary.

The pipes or high-pressure hoses between the suspension cylinders and the hydraulic cabinet, in which the pump unit, controls, valves, shut-off valves and controls are included for switching the operating conditions of the suspension units or grinding rollers are significantly reduced in their lengths and disadvantageous pipe manifold, which in the hydraulic system with a Hydraulic cabinet per pair of rollers and a loop were required are largely avoided.

The hydraulic system according to the invention provides in particular that the hydraulic cabinet with the compact hydraulic in the direct line of the outlets of the suspension cylinder or the suspension cylinder of a grinding roller is arranged so that the hydraulic oil can oscillate almost without deflection in bends and thus low resistance.

In order to ensure an approximately uniform loading of the plain bearing of Getriebeabtriebsflansches the roller mill, it is expedient after elimination of the hydraulic circuit with the hydraulic pressure compensation between the suspension cylinders of the opposing grinding rollers to provide an electrical control or regulation in which the respective oil pressures in the opposite suspension systems be measured by sensors and kept within a relatively small tolerance around a setpoint. If the setpoint is undershot, the pump of the respective hydraulic system is started or the respective discharge valve is opened for a short time.

The advantages of the hydraulic arrangement according to the invention are improved smoothness, increase in throughput and almost constant crushing forces among the grinding rolls of a roller mill and in addition to reducing the manufacturing and assembly costs, in particular with regard to the pipes to be laid, a low risk of failure of the components of the hydraulic supply units due to pre-assembled and easily replaceable hydraulic supply unit. In addition to the grinding pressure control system by means of sensors in opposite suspension units, it is also advantageous that in case of failure all grinding rollers can be raised at the same time and lifting no longer occurs depending on the hydraulic resistors successively and with a time delay.

Fig. 1

eine Prinzipdarstellung des erfindungsgemäßen hydropneumatischen Federungssystems;

Fig. 2

eine vergrößerte Darstellung eines Hydraulikzylinders des erfindungsgemäßen hydropneumatischen Federungssystems;

Fig. 3

eine vergrößerte Darstellung eines Hydraulik-Kolbenspeichers des erfindungsgemäßen hydropneumatischen Federungssystems;

Fig. 4

einen Hydraulik-Blasenspeicher des erfindungsgemäßen hydropneumatischen Federungssystems;

Fig. 5

eine stark schematisierte Darstellung einer erfindungsgemäßen Hydraulikanordnung für eine Sechs-Walzen-Mühle.

The invention will be further explained below with reference to a drawing; show in this

Fig. 1

a schematic diagram of the hydropneumatic suspension system according to the invention;

Fig. 2

an enlarged view of a hydraulic cylinder of the hydropneumatic suspension system according to the invention;

Fig. 3

an enlarged view of a hydraulic piston accumulator of the hydropneumatic suspension system according to the invention;

Fig. 4

a hydraulic bladder accumulator of the hydropneumatic suspension system according to the invention;

Fig. 5

a highly schematic representation of a hydraulic system according to the invention for a six-roll mill.

Fig. 1 shows a hydropneumatic suspension system 10 for a LOESCHE type airflow roller mill in modular design. According to the invention, each grinding roller (not shown) is associated with a suspension unit 11.

The suspension unit 11 of each grinding roller, depending on the size of the roller modules and thus in particular the grinding rollers on one or two hydraulic cylinders 12, which are connected via rocker arm 13 with the grinding rollers (not shown). The hydraulic cylinders 12 are each articulated via a hinge eye 14 with a stand 21 or mill base and a rod end 15 on the rocker arm 13.

Each suspension unit 11 of a grinding roller is assigned its own hydraulic supply unit 20. The hydraulic supply unit 20 includes motor-driven pumps, valves and shut-off devices, a grinding pressure control system and an electronic controller and controls for switching the various operating states of the roller suspension.

The hydraulic supply unit 20 is accommodated in a hydraulic cabinet 25 in a service-friendly manner, wherein it is particularly advantageous that the required pumps, valves and shut-off devices (not shown) are preassembled so that each hydraulic supply unit 20 is designed as a compact hydraulic system.

The entire hydraulic cabinet 25 with the compact hydraulic system is arranged directly on an oil tank 26, so that the compact hydraulic, for example, for larger repairs, can be easily and quickly lifted from the oil tank 26 and replaced by a unit of identical construction.

A storage stand 22 has four hydraulic piston accumulator 16, of which in the side view of Fig. 1 only one hydraulic piston accumulator can be seen, as well as 2 x four hydraulic bladder accumulators 17 on, of which in Fig. 1 only two can be seen.

Hydraulic piston accumulator 16 and hydraulic bladder accumulator 17 are combined in the accumulator 22 as a compact unit and connected via pipes 23 to the associated hydraulic cabinet 25. Fig. 1 and also Fig. 5 show that the storage level 22, based on the roller module with stator 21, suspension unit 11 and grinding roller (not shown), in front of the hydraulic cabinet 25 and in direct line with this and the suspension unit 11 is arranged.

The connection of the hydraulic piston accumulator 16 and hydraulic bladder accumulator 17 in direct line with the hydraulic cylinder 12 by means of high-pressure hoses 24 and advantageously substantially without disadvantageous manifold.

Fig. 2 shows a hydraulic cylinder 12, in which a piston 18 is guided with piston rod 19. On a piston rod side 28 each hydraulic cylinder 12 is in the installed state with a working pressure system A and the hydraulic bladder 17 and on a piston side 29 with a back pressure system G and a hydraulic piston accumulator 16 via hydraulic hoses 24 connected (see Fig.1 ).

Fig. 3 shows a hydraulic piston accumulator 16 with a piston 31 which separates a gas volume 32 in the upper region of hydraulic oil 33 in the lower region.

The in Fig. 4 shown hydraulic bladder accumulator 17 has a rubber bladder 35 and hydraulic oil 36, the level of which as well as that of the piston 31 in the shown Hydraulic piston accumulator 16 of Fig. 3 and the piston 18 in the hydraulic cylinder 12 of the Fig. 2 is determined by the operation of the hydropneumatic suspension and in the FIGS. 2 to 4 is reproduced by way of example only.

During the mill operation, the grinding rollers are lifted by the millbase lying on the mill bowl. The swing lever 13 are ausgeienkt. The pistons 18 of the hydraulic cylinders 12 move upwards and displace oil into the working pressure system A into the hydraulic bladder accumulators 17 of the associated storage rack 22 (see FIG Fig.1 ). The nitrogen-filled storage bladder 35 (see Fig. 4 ) in the bladder accumulators 17 is compressed by the inflowing oil.

At the same time works on the piston side 29 of the hydraulic cylinder 12, the back pressure system G (see Fig. 1 ). At the same moment therefore hydraulic oil 33 is by nitrogen pressure 32 (see Fig. 3 ) is pressed out of the hydraulic piston accumulator 16 back into the piston side 29 of the hydraulic cylinder.

When the grinding rollers roll into a grinding bed valley, the process reverses. In the working pressure system hydraulic oil from the hydraulic Blasenspeichem 17 in the piston rod side 28 of the hydraulic cylinder 12 ( Fig. 2 ). At the same time, hydraulic oil is displaced from the piston side 29 of the hydraulic cylinder 12 into the hydraulic piston accumulator 16. Because of the inhomogeneity of the grinding bed, the grinding rollers continuously carry out vertical movements, which is why the processes described alternate constantly.

To start and stop a roller mill, the grinding rollers can be lifted hydraulically from the grinding bed. With the hydropneumatic suspension system according to the invention, this is possible simultaneously or almost simultaneously.

In Fig. 5 a hydraulic system according to the invention for a six-roll mill in modular design is shown very schematically. The six stands 21 and the six hydraulic supply units 20, storage levels 22 and suspension units 11 of the six hydropneumatic suspension systems 10 are only indicated.

Fig. 5 conveys that the pipes 23 (see also Fig. 1 ) between the storage stand 22 and the associated hydraulic supply system 20 and the high-pressure hoses 24 between the storage stand 22 and the hydraulic cylinders 12 Each hydropneumatic spring system 10 are relatively short and therefore pipe manifolds can be omitted. The hydraulic cabinet 25 of the hydraulic supply unit 20 of each hydropneumatic suspension system 10 is in direct line with the hydraulic cylinders 12, which is why the hydraulic oil can oscillate with little resistance.

A uniform load of the respective opposing grinding rollers on the transmission (not shown) without a hydraulic loop to avoid possible bearing failure is achieved with an electrical control / regulation (not shown), in which the respective oil pressures in the opposite suspension units by means of sensors (not shown ) and kept within a relatively small tolerance around a setpoint. If it falls below the value, the pump is started in the respective hydraulic cabinet and the respective drain valve is opened for a short time. In this way, an effective pressure equalization is achieved.

Claims (5)

1. Hydraulic arrangement of a roller mill, wherein grinding rollers roll on a rotating grinding pan and on a grinding bed formed thereon by grinding material and are pressed resiliently with the aid of a hydro-pneumatic spring system (10) onto the grinding material,
   wherein one hydro-pneumatic spring system (10) with a spring unit (11) and at least one hydraulic cylinder (12) is assigned to each grinding roller and
   each hydro-pneumatic spring system (10) comprises, besides the spring unit (11), its own hydraulic supply unit (20) and its own accumulator stand (22), which are arranged in close proximity to each other and to the spring unit (11) and connected to each other or to the spring unit (11) via short lines,
   characterised in that
   the hydraulic cylinders (12) of the hydro-pneumatic spring systems (10) can be impacted on two sides,
   that each hydraulic supply unit (20) is formed as compact hydraulic unit and is received pre-assembled and in a service-friendly manner in a hydraulic cabinet (25), wherein
   each hydraulic cabinet (25) is arranged and connected with the assigned accumulator stand (22) in a direct line with the spring unit (11) of a grinding roller, and
   that each accumulator stand (22) which comprises hydraulic piston accumulators (16) and hydraulic bladder accumulators (17) is formed as a compact unit and is arranged in a direct line with the assigned spring unit (11) of a grinding roller and arranged via short hydraulic hoses (24) and also directly before the hydraulic cabinet (25) and is connected thereto via short pipelines (23).
2. Hydraulic arrangement according to claim 1,
   characterised in that
   each hydraulic cabinet (25) is arranged on an oil tank (26) and can be raised from the oil tank (26) and exchanged.
3. Hydraulic arrangement according to one of claims 1 or 2,
   characterised in that
   a grinding pressure regulating system is provided, with which a virtually uniform contact pressure of the grinding rollers of a roller mill, at least of the grinding rollers lying opposite each other, can be set.
4. Hydraulic arrangement according to claim 3,
   characterised in that
   the grinding pressure regulating system comprises sensors in the region of the spring units (11) for measuring the oil pressure.
5. Hydraulic arrangement according to one of the preceding claims,
   characterised in that
   each hydraulic cylinder (12) of a spring unit (11) is connected to the assigned grinding roller via a grinding roller swing lever (13), wherein a piston rod (19) of a piston (18) is fixed in the hydraulic cylinder (12) via a rod head (15) in an articulated manner on the swing lever (13) and the hydraulic cylinder (12) via an articulated eye element (14) on the mill lower part or pedestal (21) of a roller module.

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